Carburetor



April 25, 1933. R. F. BRACKE 1,905,435

CARBURETOR Filed March 4, 1951 2 Sheets-Sheet 1 flaw /7 if a April 25, 1933.

R. F. BRACKE 1,905,435

CARBURETOR Filed March 4, 1931 2 Sheets-Sheet 2 Patented Apr. 25, 1933 UNITED 1 STATES ROBERT F. nnnoxn, or CHICAGO, ILLINOIS, AssIeNon,-B,MnsN Ass/IeN E rrs 'ro LYNN A. WILLIAMS, or EVANSTON, ILLINoIsn D QLIEFORD o. B AD U Y, or

GLENcoE, ILLINoIs, AS TRUSTEES cnniaunnron Application filed March4f1931. Seria1". No.j 2O,032. j

My invention relates to carburetors and connection with two cycle motors.

One of the objects of thepresent invention "5 is the provision of a'carburetor which has good volumetric efficiency, that is large enough to spermit the motor to produce its maximum horse power without sacrificing any performance orsmoothness in thelower more particularly to carburetors for use'in' or part throttle range where the .amount of fuel and air delivered by the carburetor is relatively small. i

A further object of my invention is the provision of means for providing maximum '15 atomization and breaking up of the fuel to permit easy starting, good economy, and' plurality of-cylgood distribution where a inders are fed from a single device. s

A further object of my invention is the provision of means for utilizing a plurality of efficient Venturi tubes for the purpose of delivering sufficient fuel for all engine demands and for thoroughly atomizing the fuel under a comparatively low. mixing chamber depression.

The invention further consists in certain novel features of construction, combinations and arrangements of the several parts whereby certain important advantages are attained '30 as will hereinafter be more clearly set fort-h in connection with the accompanying drawings showing one form of my invention and in which I T 1 Fig. 1' is a plan viewof a carburetor embodying the principles of my invention, and Fig. 2 is a sectional view taken on the line 22 of Fig. 1 looking in the direction indicated by the arrows.

. Fig. 3 is a transverse sectional view taken 4 along the line 33 of Fig. 2 lookingin the direction indicated 'by'the arrows, and

Fig. 4 is a view partly in elevation and partly in section showing the idling system pf the carburetor and the adjustmentthere- O1. 1

' Similar characters 'of reference refer to similar parts throughout 'theisever'al views.

The carburetor here shown is designed particular-ly for usewith two cycle outboard motors V in which amechanically operated valve is used'between thecarburetor and the crankcase. of the moto-r-forthe purpose of admitting to the crankcase as'much charge as is possiblefor the greatest power output.

Referring first to Fig. 2, 5 designates the carburetor bodyarranged to form the mixing chamber 6 and the-flange -7, the latter being arranged for attachment to the :rotor. housing orcrankcase ofthe motor. Extending vertically through the llOllSiIWif) is athrottle shaft 8 carryingtheyusual t rottle plate 9 and a throttle lever 101 Extending parallel withthe throttle shaft is:a second shaft 11 carrying a plate 12 and hand lever.13, this combination forming the choke arrangement of the carburetor. An airhorn' 14 is attached to the intake end' ofthe carburetor and is providedwith a weather capql5 extending over the horn'in a manner to prevent water from splashing into thescarburetor during the operationof the device. Interposed between the throttle and-choke plates!) and12 respectively and located in themixing-chamberof the carburetor is a large 'Venturi tube 1.6,, which, as shown in Fig. 3, is slottedat 16; The outside diameter of this large Venturi tube is slightly more than1the inside diameter of the mix ing chamber. In the process of assembly the large Venturi tube 16 is compressed radially and then inserted to its proper place in the mixing chamber. Upon being released the tube springs outwardly to'assume its original shape andsize' and thereby clings tightly to the inner wall-of the body 5 and thus prevents rattling of the parts during operation. U v Extending through the carburetor body 5 as most clearly shown in F ig'.-'3 are two primary Venturi-tubes 17 and 18 eachhaving 0 its air entrance end 19 in direct communica tion with the chamber 20 formed by the cover 21. The chamber 20 has communication with atmosphere through .opening 22 shown in Fig. 2. The exit end 23 of each of the primary Venturi tubes extends into the mixing chamber of the carburetor and as shown in Fig. 3 the two tubes are arranged one on each side of the center line of the carburetor. Each of the primary Venturi tubesi17; and 18 is provided with .a-throat 24 having a series of fuel jets 25 therein communicating between the throat of the Venturi than; annular chambers shown at 26.

and the annular chambers 26 is the fuel passage 27 communicating with the vertical passage 28 in turn communicating'with the passage 29 extending intothe float chamber 20 passage 29 *is'zprovided -withza. brass seat 31 arranged "to cooperate" with the .main needle valve 32 preferably-madeiof stainless steel or some otherfnoncorrosive material. The needle valve 32 has a serrated head 33 ar- :ranged forcooperation'with a spring-pressed idetenti34=mounted in the cover 21. V Fromithe'description thus far described it will The apparent :that-JalI of the ifuel de- 'ilivered from thefioat chamber to the pri- -mary Venturi tubes 17 and 18 can be conitrolledrbythe needle valve 32;

.=Extendingrthrougl the floor of'the float chamber 30 and :preferably cast therein is a :brass Iinsert '35-fprovided with a float valve seat .36 arranged to cooperate with the float valve=37icarried by the float pin 38; 39 designates-afloat preferably made of cork and at tachedtothepin 38 at theproper height bysmeansof the clip shownat 40. The uprper end of the float pin 38 extends loosely :through the cover/21, this-bearing forming "as guideto keep the float mechanism in alignment for proper operation. The lower end iofthe brass insert is threaded asshown to cooperate withthescrew f41 arranged to secure thestrainer housing 42 to the underside 'ofthe float bowl. This strainer housing is most clearly shown in-Figr-3 and-has the upper surface 43 chamferedto press against the fibre,- cork or other softwmaterial gasket shown at The fuel intake for the strainer housing'is shown-at 45 arranged to feed fuel to the undersideiof the strainer 46. This strainer-is preferably made up' 'of' brass or'copper wire mesh and is shaped was to "bear lagainstzthe lower end ;of the brass insert- 35 and the'chamferedsurface 43 of :the strainer r'housing'iwhen the parts are assemibledi The screw-41:maybe provided with cotter lpin or -:wire='47 to prevent the disassembling of this screw from the strainer housing when the housing is removed for the purposemf'cleaningthe strainer; r 5 Referring nowto theidlingfsystem of the Extending transversely through the 'body 5 30 of the carburetor. The upper end of the carburetor which is most clearly shown in Fig. 4, 48 designates a fuel passage extending'between the float chamber and the vertical passage 49 terminating at its upper end in the threaded portion 50 into which is screw threaded the idle plug seat 51. This piece 51 is preferably made of brass and is provided as shown with the seat 52 and the transverse openings 53. Cooperating with the seat 52 is a needle valve 54 extending downwardly through'the housing 21 and arranged for cooperation detent similar to the detent 34 used on the main-needle valve. I

The transverse openings 53 have communication with the annular chamber55 which in turn has communication with atmospherethrough the passage shown in dotted lines .at 5.. The annular-chamber 55 also communicates with the vertical passage 57 in turn communicating with o the horizontal passage 53running longitudinally along the side of the mixing chamber 6. The outer end of the passage 58 communicates with the two holes 59 and 60 extending into the niixing cham'' ber, these holes beingso-arranged;that when with a spring pressed the'throttle-is closed or nearly closedasfor :the lowest idle the opening 59. is disposed on the engine side of the throttle and the opening .60 on the mixingcha'mber side thereof. iln this throttle position the comparatively high manifold suction of theengine' at idle is communicated through the opening 59 .into thepassage 53 which results in airboing taken "in from the mixing chamber through the opening '60. A suction or :re-

duct-ion of pressure-is also provided in passage 57 and annular chamber 55 resultingiin the intake of air through-the .passagef56-and the delivery vof fuel from the passage 149 through :the valve seat52 and finto'the annular chamber55, the amount of 'fuel delivered of course depending upon the needle valve :setting. The air'intake zpassage 5'6 and annular chamber 55 are located above the znormal leVel of the fuelias shown in dotted lines in F ig. .3 so that WllGDftllG motor is standing idle there can 'beno'tendency-for the fuel'to siphon out. of'the-'flo-at chamber through theidle system and into the mixing chamber through the holes. 59and 60.

The operation of the carburetor embodying my invention as above describedrisas fol- -lows: Instarting the motor the choke plate 12 is closed and the throttle Q'opened'toab-ou't one quarter iopen position. The iiiain iiee(ll e valve 32 isopen-ed about one-turn'as is the'idle needle valve 54. The moto'r is t'hen cranked to producea comparativelyhigh suction or depression in themixing chamber: 6 'whichae sults in a;high velocityai'r-gflowthrough the two primary Venturi tubes 17 and 18. This high velocity. air flow produces a high sucv.tion or reduction ofl taressurein the throa'tsj24 of the Venturi tubes-and causes fuel to flow from the float, chamber 30 through the various passages of the high speed systemand through the jets 25 in the primary Venturi tubes where the fuel is mixed with the high 1 Upon starting of the motor the choke is opened to its full open position as shown in Fig. 2 and the main needle valve 32 given its proper setting for best performance at wide open throttle position. The throttle is then closed or nearly closed for slow running and the idle needle 54 adjusted in or out for the best hitting at this throttle position.

Because of the arrangement of the primary Venturi tubes it is possible to obtainsuflicient suction at the throats of the Venturi tubes for the delivery of the proper amount of fuel for all engine demands even though the mixing chamber 6 is made comparatively large and therefore has a comparatively low suction or reduction of pressure during the operation of the motor. By the arrangement of Venturi tubes asshown I am enabled to multiply the comparatively low suction of the mixing chamber to a point where proper fuel delivery is assured.

Attention is also called to the fact that the Venturi tubes 17 and 18 are arranged to deliver downwardly so that there is no loss in etficiency as would be the case if the Venturi tubes delivered up or horizontally.

Another feature of the invention is the fact that the Venturi tubes 17 and 18 deliver fuel into the mixing chamber of the carburetor at right angles to the air flow. This arrangement results in a thorough breaking up or atomizing action of the fuel in the mix ing chamber and tends toward good economy and good motor performance. The symmetrical location of the nozzles 17 and 18 with respect to the mixing chamber 6 as shown in Fig. 3 aids materially in the proper atomization and distribution of the comparatively rich mixture delivered by the Venturi tubes. By the use of two Venturi tubes the primary mixture is discharged into the secondary airstream in two separate and distinct streams each representing a proportionate amount of the quantity delivered for any position of the throttle thereby distributing the mixture across the entire secondary air stream instead of a portion thereof which is the case where a single common type'of jet or where a single Venturi tube is used.

While I have illustrated and described my invention as'applied to two cycle motors of a certain type it is to be understood that certain features of this invention may be applied for use in connection with various types of motors and other types of carburetors two distinct streams.

and throats'of said fuel maybe withdrawn from the fuel chami charged J into said vided with a venturi,

without departing from'the spirit'and scope of this invention. v

Iclaim: a i 1. In a carburetor, having a mixing chamher through whicha stream of secondaryair is adapted to pass, a pair of suction multiplying Venturi tubes extending into saidchamber andterminating therein and constituting the primary air inlet of the carburetor, said 7 tubes being 5 located symmetrically with respect. to a diameter of the'm ixing chamber, a fuel chamber, a passage interconnecting the fuel chamber andthroats of saidpVenturi tubes whereby fuel maygbe drawn into the primaryair stream from said fuel chamber and discharged into the mixing-chatnbefr in "chambena passage therefrom interconnect- 2. a carburetor, amixing chamber provided jwith a venturi, a pair of suction multiplying Venturitubes pro ecting transversemg the fuel chamberand the throats of said Venturi tubes whereby "fuel may be withdrawn fromthe fuel'chamber into the primary air stream'of said pair of tubes anddischarged in said m xmg chamber, in two distinct streams.

3. In a carburetor, a mixing chamber, a

pair of suction multiplying Venturi tubes disposed transversely in said chamber, said tubeshaving' air'intake ends exposed'to atmosphere and discharge ends which project downwardly into said chamber and are located. therein to supply'a mixture of air and fuel in said chamber, a fuel chamber, apassage therefrom connecting the fuel chamber Venturi tubes whereby ber into the airstream of'saidVcnturi tubes and discharged in 'said' mixlng chamber 1n "chamber at saidrestriction tojprovide a, pri- 7 mary inlet for said carburetor, said Venturi tubes being arranged vertically soasto'discharge downwardly and being locatedsymmetrically with respect to a vertical diameter of'the chamber, a fuel chamber, a passage the respective thr oatsof the Venturi tubes whereby fuel may be withdrawn from the chamber to form a primary air inlet for said therefrom connectingffthe fuel chamber anda mixing chamberv pro carburetor and adapted ,to discharge into said venturi, a secondary air inlet for said carburetor, means governing the flow of the Secondary-air stream into said chamber, a

i'ii fuel chamber, a passage therefrom connect- .ing gthetfuel chamber and the throats .of the Venturi tubes-whereby fuel may be with- ;drawn from the fuel chamber into the .respective tair strea-msof the Venturi tubes and a! discharged into the secondary air stream .in

--stantially constant twodistinct streams;

5. In avcarburetor, [a mlxing chamber, a

,pairof spaced suction multiplying Venturi tubes disposed transversely in said chamber, said tubes haying intakeends exposed to'atimosphereand dischargerends located within said chamber to supply a primary mixture o f. air and fuel in said chamber, said tubes being located symmetrically with respect to to deliver :two distinctand Separate primary air streams downwardly into the mixing chamber, a fuel chamber at positionsiwithin said enturi, and-,a passageextending from the fuel chamber to the throats ofthe Venturi tubes. 1

I In witness whereof, I hereunto subscribe my ,namethis 518th day of February, 1931.

ROBERT BRAOKE.

a .yertiealdiameter o'f'the mixing chamber, .a secondary air inlet for said carburetor, a

a fuel ,chamber, .a passage from said :fuel

chamber iconnectlng the fuel chamber and respectivethroatsof said Venturi tubes, discharge nozzles ,for said Venturi ,stubes subjected to mixing chamber depression whereby ,fuel may be-drawn .from ;said fuel chamber and fed inslike amounts through said passage into the respective primary air streams and discharged through said nozzles .into \thefsecondary' air passage in two distinct streams at right angles thereto.

j 8. \In la-carburetor, a mixing chamber, extending substantially horizontally therethrough and 1 provided with a .venturi, a pair .of .-suction multiplying Venturi tubes substantially vertically disposed -.and arranged itosdeliver twodistinct and separate primary iair streams downwardly into the, mixing chamber,= a .fuel. chamber atpositions within isaidwenturi means for maintaining a subfuel level slightly below wthe throatslo'f the Venturi tubesand a passage,extendingfromthe fuel chamber tothethroats of the Venturi tubes. I v 9. In ,acarburetona vmixil ig chamber ex- ,tending substantially horizontally there- -throi igh,zand\provided witha-Yenturi, a pair of suction multiplyingvYenturi tubes substantially vertically disposed and arranged CERTIFICATE or CORRECTION.

Patent No. 1,905,435. April 25, 1933.

ROBERT F. BRACKE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, lines 55 and 68, claims 8 and 9, respectively, strike out: the comma and words a fuel chamber", and in lines 56 and 69, after "venturi," insert the words "a fuel chamber,"; and that the said Letters Patent should be reed with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of July, A. D. 1933.

M. J. Moore.--

(Seal) Acting Commissioner of Patents. 

